Device for manufacturing a stator

ABSTRACT

The method for manufacturing a stator of an electric machine includes providing a lamination element extending over an annular sector, horizontally moving the lamination element towards a fitting zone, then angularly regulating the lamination element position, and connecting the lamination element to other lamination elements to define the stator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a divisional application ofpending U.S. application Ser. No. 14/154,597, filed Jan. 14, 2014, whichclaims priority to European application 13151203.0 filed Jan. 14, 2013,the contents of each hereby incorporated in their entirety.

TECHNICAL FIELD

The present disclosure relates to a method and a device formanufacturing a laminated stator core.

The laminated stator core can be a part of an electric machine such as asynchronous generator to be connected to a gas or steam turbine(turbogenerator) or a synchronous generator to be connected to a hydroturbine (hydro generator) or an asynchronous generator or a synchronousor asynchronous electric motor or also other types of electric machines.

BACKGROUND

A laminated stator core is made by a plurality of laminations that arestacked and fixed together to form an annular body.

In order to manufacture the stator, EP 1 592 110 discloses to group anumber of laminations together to form “donuts” (i.e. annular elementsmade of a plurality of laminations) and to horizontally stack thedonuts.

In addition, EP 1 592 110 also discloses a device having a rail withremovable supports and a dolly movable on top of the rail; the dolly hasa saddle that can hold the donuts.

During operation, the donuts are provided on top of the saddle, and thenthe dolly is moved towards the stator that must be manufactured.

In order to support the rail, a plurality of supports must be connectedto the rail and, when the dolly with a donut on it must cross a support,this support is removed while other supports are not (i.e. one supportis removed while other supports are not removed such that the dolly cancross the zone from which the support has been removed while the rail issupported by the other supports).

Then the removed support is connected to the rail again and anothersupport is removed, until the dolly reaches its final position toassemble the donut to the stator.

Because of the need to connect and disconnect the supports from therail, manufacturing can be time consuming.

SUMMARY

An aspect of the disclosure includes providing a device and a method bywhich manufacturing time can be optimised.

In particular, time manufacturing is optimised because the need toconnect and disconnect the supports to and from the rail is limited oravoided.

These and further aspects are attained by providing a device and methodin accordance with the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages will be more apparent from thedescription of a preferred but non-exclusive embodiment of the methodand device, illustrated by way of non-limiting example in theaccompanying drawings, in which:

FIG. 1 is a schematic side view of a device of the disclosure;

FIG. 2 is a schematic front view of a particular of the device;

FIG. 3 is a particular of a rail and dolly of the device;

FIGS. 4 through 6 show examples of annular sector laminar elements;

FIGS. 7 through 10 show steps of the method;

FIGS. 11 and 12 show front view of the annular sector laminar elementsof a stator,

FIGS. 13 and 14 show detail of the method and stator realised accordingto the method.

DETAILED DESCRIPTION

The method for manufacturing a stator of an electric machine comprises:

-   -   providing lamination elements 2 extending over an annular        sector, i.e. they do not define a closed annular element,    -   horizontally moving the lamination element 2 towards a fitting        zone 3, then    -   angularly regulating the lamination element position (as        indicated by arrow F),    -   connecting or fixing the lamination elements 2 to other        lamination elements 2 to define a stator 6.

The lamination elements 2 can be defined by single metal sheets 2 a thatextend over an annular sector but preferably they are defined by a groupof metal sheets 2 a held and/or connected together and preferablyimpregnated with a resin as for example described in U.S. Pat. No.6,201,334 or also EP 1 592 110; however different methods like simpleimpregnation processes (i.e. not necessary vacuum-pressure impregnation,like simple resin dipping) can be followed as well. In addition, alsoother methods to connect together the metal sheets 2 a are possible.

All the metal sheets 2 a of a lamination element 2 extend over anannular sector and preferably have the same shape and dimension.

When connecting the lamination elements 2, in a plane perpendicular to astator longitudinal axis 7, a gap 8 is generally obtained betweenadjacent parts 9 of the lamination elements 2; for example, insulation10 can be provided in the gap 8, but this is not mandatory. Theinsulation 10 can be resin and/or a mica or mica containing element. Theinsulation is shown in connection with the embodiment of FIG. 12, but itcan be used together with any embodiment of the invention.

The method can be used as a repair method for stator cores (but this isnot mandatory), in this case before horizontally moving the laminationelements 2 towards the fitting zone 3, one or more lamination sheets 2 aor lamination elements 2 are removed from an existing stator 6 and thenthe lamination elements 2 are moved towards the fitting zone 3 and fixedto the existing stator 6 to replace the lamination sheets 2 a orlamination elements 2 that were removed.

The lamination elements 2 have indentations 11 that when the laminationelements 2 are connected each other define stator slots. Preferably,after angularly regulating the lamination element position and beforeconnecting the lamination elements 2, the lamination elements 2 arealigned. Alignment is carried out with respect to the indentations 11.

For example, the alignment is carried out by providing a templateelement 12 (for example in the form of a dummy bar) in the indentations11. This way the lamination elements 2 are aligned at the slots, thusproviding a smooth surface of the stator slot, which can be efficientlyin contact to the external surface of the stator bars; this provides agood electrical connection between the surfaces as well as a propermechanical fixation of the stator bars, thus reducing the likelihood oflocal partial discharges and/or vibrations during operation, otherwiseboth effects can give rise to accelerated aging and ultimately toelectric machine failures. In this case, provision of more than twolamination elements such as four or also more in each planeperpendicular to the axis 7 can be advantageous, because the alignmentat the indentations 11 can be improved and the overall core stackingoperation is faster. It is anyhow clear that such an alignment isadvantageous also with only two lamination elements 2 in each planeperpendicular to the axis 7.

The present invention also refers to a device 15 for manufacturing astator 6 by stacking lamination elements 2.

The device comprises:

-   -   a rail structure 17,    -   supports 18 for the rail structure 17,    -   a dolly 20 on the rail structure 17 capable of traversing at        least a portion of the rail structure 17,    -   a saddle 21 connected to the dolly 20 tailored to compliment an        upper inner diameter on the lamination element 2,    -   blocking elements 23 for holding the lamination element 2 on the        saddle 21,    -   a revolving support 25 for the saddle 21, to angularly regulate        the saddle position.

FIG. 3 shows an example of a dolly 20; in particular this figure showsthe rail 17 and the dolly 20 that is provided with rollers 26 to drivethe dolly movement on the rail 17.

The blocking elements 23 are arranged to withhold the lamination element2 preventing their separation from the saddle 21 during angularregulation.

For example, the blocking elements 23 are defined by clamps.

The operation of the device 15 is apparent from that described andillustrated and is substantially the following.

The rail 17 is assembled with the supports 18 first.

Than the dolly 20 with the revolving support 25 and the saddle 21 areprovided on the rail 17.

Thus, a lamination element 2 is provided on the saddle and is blockedthrough the blocking elements 23.

The dolly 20 is thus moved towards the fitting zone 3 (FIG. 7); sincethe lamination elements 2 are not annular but they define an annularsector, they can cross the whole rail 17 without the need of removingand reconnecting the supports 18 (see FIG. 1), to allow the passage ofthe dolly 20 with the lamination element 2 on it; this reduces themanufacturing time of the stator.

At the fitting zone 3, the saddle 21 is angularly rotated on therevolving support 25 as indicated by arrow F to bring the laminationelement 2 to the correct position for its connection to the stator(FIGS. 2 and 8). Once in the correct position, the lamination element 2is disconnected from the saddle 21 and connected to the stator 6; thedolly 20 is thus brought back to its original position to take anotherlamination element 2 (FIGS. 9 and 10).

In one embodiment shown in FIG. 14, when the angular position of thelamination element is regulated and adjusted, the gaps 8 of successivelamination elements are not aligned along the axis 7, for example toimprove the overall core stiffness and to prevent mechanical andelectrical resonances that could cause vibrations and damage of thestator or defective operation.

Naturally the features described may be independently provided from oneanother.

In practice the materials used and the dimensions can be chosen at willaccording to requirements and to the state of the art.

The invention claimed is:
 1. A device for manufacturing a stator bystacking lamination elements, the device comprising: a rail structure;supports for the rail structure; a dolly on the rail structure operableto traverse at least a portion of the rail structure; a saddle connectedto the dolly, the saddle complimenting an upper inner diameter of an atleast one lamination element; blocking elements arranged on opposedsides of the saddle for holding the at least one lamination element onthe saddle between the blocking elements; and a revolving support,arranged between the dolly and the saddle, operable to angularlyregulate positioning of the saddle.
 2. The device according to claim 1,wherein the blocking elements prevent separation of the at least onelamination element from the saddle.
 3. The device according to claim 2,wherein the blocking elements comprise clamps for clamping the at leastone lamination element between the blocking elements.